In a conventional storage-battery charge/discharge system, for example, a charging method for bringing a storage battery into a full charge state at the time of use is disclosed. The method includes an input step to input a starting date and time of using the power stored in the storage battery; a first charge control step to control charge of the storage battery by a control means so as to bring the charge amount of the storage battery to a first charge amount predetermined; and a second charge control step to control charge of the storage battery by the control means so as to complete the charge, at the starting date and time of use inputted in the input step, to a second charge amount (full charge) predetermined that is larger than the first charge amount (for example, refer to Patent Document 1).